Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 microM did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron (24.6 +/- 2.1%) compared with 62.7 +/- 2.8 and 63.1 +/- 1.4% of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed 69.1 +/- 4.3% and 72.6 +/- 5.7% of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells (2.8 +/- 0.2%). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.
Animals ; CHO Cells ; Cell Adhesion/drug effects ; Cell Survival ; Cricetinae ; Cricetulus ; Entamoeba histolytica/*drug effects/*physiology ; Iron/*pharmacology

Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 microM did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron (24.6 +/- 2.1%) compared with 62.7 +/- 2.8 and 63.1 +/- 1.4% of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed 69.1 +/- 4.3% and 72.6 +/- 5.7% of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells (2.8 +/- 0.2%). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.
Animals ; CHO Cells ; Cell Adhesion/drug effects ; Cell Survival ; Cricetinae ; Cricetulus ; Entamoeba histolytica/*drug effects/*physiology ; Iron/*pharmacology

Entamoeba histolytica is an enteric tissue-invading protozoan parasite that can cause amebic colitis and liver abscess in humans. E. histolytica has the capability to kill colon epithelial cells in vitro; however, information regarding the role of calpain in colon cell death induced by ameba is limited. In this study, we investigated whether calpains are involved in the E. histolytica-induced cell death of HT-29 colonic epithelial cells. When HT-29 cells were co-incubated with E. histolytica, the propidium iodide stained dead cells markedly increased compared to that in HT-29 cells incubated with medium alone. This pro-death effect induced by ameba was effectively blocked by pretreatment of HT-29 cells with the calpain inhibitor, calpeptin. Moreover, knockdown of m- and micro-calpain by siRNA significantly reduced E. histolytica-induced HT-29 cell death. These results suggest that m- and micro-calpain may be involved in colon epithelial cell death induced by E. histolytica.
Calpain/antagonists & inhibitors/genetics/*metabolism ; *Cell Death ; Cell Line ; Cell Survival/drug effects ; Dipeptides/metabolism ; Entamoeba histolytica/*pathogenicity ; Epithelial Cells/*parasitology ; Gene Knockdown Techniques ; Humans

One of the most common drugs used against a wide variety of anaerobic protozoan parasites is metronidazole. However, this drug is mutagenic for bacteria and is a potent carcinogen for rodents. Thymus vulgaris is used for cough suppression and relief of dyspepsia. Also it has antibacterial and antifungal properties. The aim of this study was to investigate antiamebic effect of Thymus vulgaris against Entamoeba histolytica in comparison with metronidazole. One hundred gram air-dried T. vulgaris plant was obtained and macerated at 25 degrees C for 14 days using n-hexane and a mixture of ethanol and water. For essential oil isolation T. vulgaris was subjected to hydrodistillation using a clevenger-type apparatus for 3 hr. E. histolytica, HM-1: IMSS strain was used in all experiments. It was found that the minimal inhibitory concentration (MIC) for T. vulgaris hydroalcoholic, hexanic extracts, and the essential oil after 24 hr was 4 mg/mL, 4 mg/mL, and 0.7 mg/mL, respectively. After 48 hr the MIC for T. vulgaris hydroalcoholic and hexanic extracts was 3 and 3 mg/mL, respectively. Therefore, it can be concluded that the Iranian T. vulgaris is effective against the trophozoites of E. histolytica.
Animals ; Antiprotozoal Agents/chemistry/*pharmacology ; Dose-Response Relationship, Drug ; Entamoeba histolytica/*drug effects ; Iran ; Metronidazole/pharmacology ; Microbial Sensitivity Tests ; Plant Extracts/chemistry/*pharmacology ; Plant Oils/chemistry/pharmacology ; Thymus Plant/*chemistry